Computer security in a shared environment—e.g., healthcare or manufacturing—is essential for preventing unauthorized intruders from accessing sensitive or classified information and data within the computer system. Authentication is the act of accepting proof of identity given by a trusted person; such proof may be based on one or more of three unique factors: something the person knows (e.g, a password or PIN); something the person has (e.g., a badge, token or cell phone); or something the person is (e.g., a biometric indicium such as a fingerprint). Very high security requirements may include the concept of a “mantrap”—i.e., a physical space bounded by different sets of doors arranged such that one set of doors must close before the next set can open. Different factors of authentication are usually required through each door or authentication gate.
This notion of requiring performance of sequential actions for authentication may be replicated electronically through quorum-based schemes. In such approaches, authentication requires the presence of, or actions taken by, a threshold number of members of a defined group. For example, one or more access sets, each containing a threshold number of group members, may be defined. The group members may split a quorum private key, in which case the shares of the quorum private key for each group member in all access sets are specified. The shares of the private key held by the group members in any one access set add up to a number directly related to the private key. See, e.g., U.S. Pat. No. 7,136,489.
Conventional quorum-based approaches are limited, however, in that group members must ordinarily, and independently, perform some physical action to manifest their presence and identify themselves. Moreover, that activity generally involves separate communication between each group member and a central authentication server. These requirements limit the appeal and adoption of quorum-based authentication systems.